Heat Pump vs Gas Boiler Cost Calculator

Compare a year of heating with a heat pump versus a gas boiler using your heat demand, the heat pump COP, boiler efficiency and fuel prices.

A heat pump turns each unit of electricity into several units of heat, but electricity costs more than gas per kWh — so which wins depends on your numbers. Enter your yearly heat demand, the heat pump's seasonal COP, your boiler efficiency and both fuel prices to compare a full year of heating.

Side by side

How the math works

The heat pump's electricity use is heat demand ÷ COP; its cost is that times your electricity price. The boiler's gas use is heat demand ÷ efficiency; its cost is that times your gas price. The saving is the difference (floored at zero).

Worked example: 12,000 kWh of heat with a COP of 3.3 needs 3,636 kWh of electricity, costing $909 at $0.25/kWh. A 92% boiler burns 13,043 kWh of gas, costing $1,174 at $0.09/kWh. The heat pump saves about $265 a year.

Assumptions and limits

COP is not fixed — it falls in cold weather and with high-temperature radiators, so use a realistic seasonal COP (often 2.8–3.8), not the lab peak. Prices are volatile and vary by country and tariff, which is what usually decides the winner. This ignores installation cost, maintenance and any grants; it compares running cost only.

When this calculator helps most

This is built for a genuine before-you-buy decision — comparing a heat pump quote against staying on gas for your specific home, not a generic "heat pumps are greener" comparison. Because the result flips entirely based on your local electricity-to-gas price ratio and your realistic seasonal COP, running your own numbers matters far more here than for most calculators on this site.

Mistakes that throw off the estimate

The single biggest one is using a heat pump's peak lab COP instead of a realistic seasonal average. Manufacturers quote COP at a specific, favourable outdoor and flow temperature; across a real heating season — including the coldest days, when a heat pump works hardest and its COP drops the most — the achieved average is usually meaningfully lower. Use 2.8–3.8 as a realistic seasonal range unless you have monitored data for your specific system, and treat any single quoted "COP of 5" figure as a best-case, not a planning number.

What this comparison doesn't capture

This tool compares running cost only — it says nothing about the upfront cost of installing a heat pump, which is typically far higher than a like-for-like gas boiler before any grant or subsidy, or about how long that difference takes to earn back at the yearly saving this calculator shows. It also doesn't account for a heat pump often requiring larger radiators or underfloor heating to work efficiently at lower flow temperatures, which can add to a retrofit's cost beyond the unit itself. Government grants and incentives for heat pump installation exist in many countries and can change the upfront-cost side of the decision substantially — worth checking what's available locally before treating running-cost savings alone as the full picture.

What it costs in practice

Yearly electricity cost of a heat pump by the home's heat demand and its efficiency (COP), at $0.17/kWh. A COP of 3.5 means 3.5 kWh of heat per kWh of electricity.

Your own price and habits change these — the calculator above uses your numbers.

Frequently asked questions